UITableView scrollToRowAtIndexPath problem

Question

I'm trying to make my table view remember it's last position, so that after the app is run again, it will scroll to that position. to do this, in my viewWillDisappear: method, I get the first visible row number and save it to NSUserDefaults. then in my viewDidAppear I try to scroll to that row by sending scrollToRowAtIndexPath to the table view. However I get a NSRangeException:

*** Terminating app due to uncaught exception 'NSRangeException', reason: '-[UITableView scrollToRowAtIndexPath:atScrollPosition:animated:]: section (0) beyond bounds (0).'

any help appreciated. Here is the code:

- (void)viewDidAppear:(BOOL)animated
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

    if ([userDefaults valueForKey:@"content_row"] != nil)
    {
     int rowToHighlight = [[userDefaults valueForKey:@"content_row"] intValue];
     NSIndexPath * ndxPath= [NSIndexPath indexPathForRow:rowToHighlight inSection:0];
     [contentTableView scrollToRowAtIndexPath:ndxPath atScrollPosition:UITableViewScrollPositionTop  animated:YES];
    }
}

-(void) viewWillDisappear:(BOOL)animated
{
    NSIndexPath *selectedRowPath = [[contentTableView indexPathsForVisibleRows] objectAtIndex:0];
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setInteger:selectedRowPath.row forKey:@"content_row"];
}

Answer 1

It's possible that the contentTableView has not yet finished loading the data.

Answer 2

Reload TableView data before calling scrollToRowAtIndexPath.

[contentTableView reloadData];